The present invention relates to biopsy needles for sampling tissue and the like and, more particularly, to biopsy needles having a one-way valve arrangement allowing for secure removal of biopsy samples from a subject for histological assessment.
Through use of biopsy needles, most organs of a body can be biopsied with varying degrees of difficulty, danger and discomfort. While some organs of a subject patient can be biopsied with relative ease and minimal discomfort, using local anesthetic, skillful operation and use of general anesthetics are required to biopsy other organs. The degree of danger involved in the biopsy of a given organ is balanced against the benefits of having the tissue available for histological examination.
Due to a number of factors, such as the nature of the disease encountered in a given community and the incidence of that disease, some types of biopsies must be performed more frequently than others. For some diseases, it is sometimes necessary to obtain biopsies at intervals to follow the progress or regression of disease states. This is the case with liver disease and bone marrow disease.
Various problems may arise as a result of needle biopsy. First, due to the technical difficulty of retaining a biopsied specimen within the lumen of the needle, the quantity of tissue obtained is too small to be useful, and occasionally, no tissue is obtained at all. Second, damage to extracted tissue can occur because of mechanisms currently employed to retain tissue in the lumen of the needle during removal. Third the patient can be exposed to greater risk of damage when larger needles are employed. Finally, in the case of bone marrow biopsies, it is frequently necessary to rock the needle backwards and forwards, thus causing considerable discomfort for the patient.
Several needles have been introduced in the past for producing good-sized biopsy specimens suitable for histological assessment. The Menghini needle comprises a needle with a syringe on one end. The syringe is actuated so as to create negative pressure within the needle lumen as the needle is advanced into the tissue. The negative pressure is used to retain the biopsied specimen in the lumen of the needle as it is removed. The Menghini needle does not always perform its intended purpose, particularly in situations where the diseased tissue is very fibrous and hard. Additionally, the Menghini needle depends on considerable operator skill in order to provide proper and consistent use.
A Tru-cut needle is illustrated in Mehl U.S. Pat. No. 4,733,671 and Beraha U.S. Pat. No. 4,600,014. The Tru-cut needle includes a gutter drilled out of one end. As best illustrated in FIGS. 4-6 of the Beraha patent, a gutter penetrates the tissue such that the tissue falls into the gutter, so that as a metal sheath is passed over the opening of the gutter, a tissue sample is cut off. The Tru-cut needle tends to be rather large and needs considerable operator skill to produce consistently good samples.
The Vim Silverman needle, as best illustrated in Silverman U.S. Pat. No. 2,198,319 comprises a metal device split down the center with a natural inclination for two pieces to diverge from one another when pushed forward out of an accompanying sheath. Subsequent to penetrating tissue with the two pieces, the sheet is passed over the top of them, squeezing the tissue into place so that it can be withdrawn.
The Jamshidi needle is typically used for obtaining bone marrow biopsies. The needle comprises a hollow tube, one end of which is swaged to taper the end. As the tapered end penetrates bone marrow, a core of the tissue, having a diameter equal to the opening of the tapered end of the needle and less than the diameter of the body of the tube, passes into the lumen of the needle the tapered end of the needle is manipulated in order to cut off the cored tissue.
Russian Patent No. 553,970 discloses a biopsy instrument comprising a hollow needle having a sharpened end and a machined interior, rearwardly sloping and facing annular cutting ridge. Pegg et al. U.S. Pat. No. 4,649,918 is similar, in that it comprises a hollow needle with a bone cutting leading edge and three inwardly radiating machined teeth adjacent the cutting edge which occlude 10 to 20 percent of the cross-sectional area of the interior of the hollow needle. The needles in both of these references have to be machined in order to achieve the structure as shown. Further, it appears that there is a serious question as to how much of the specimen these two needles would retain in soft tissue, in that neither appears to occlude a considerable cross-sectional area of the interior of the needle.